CN103436679B - Differential temperature heat treatment method of minor-diameter high chromium cast-iron roll - Google Patents
Differential temperature heat treatment method of minor-diameter high chromium cast-iron roll Download PDFInfo
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- CN103436679B CN103436679B CN201310327096.8A CN201310327096A CN103436679B CN 103436679 B CN103436679 B CN 103436679B CN 201310327096 A CN201310327096 A CN 201310327096A CN 103436679 B CN103436679 B CN 103436679B
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Abstract
The invention discloses a differential temperature heat treatment method of a minor-diameter high chromium cast-iron roll, which comprises the steps of roll neck bush welding, heat pretreatment, differential heating, precooling treatment, quenching & cooling, tempering treatment, roll neck bush removal and the like for the minor-diameter roll to achieve differential temperature heat treatment production of the minor-diameter roll. The method is simple and reasonable in technology; the roll is equipped with a roll neck bush, and an air-fuel ratio of a differential temperature furnace burner is adjusted, so that the heating capacity of a furnace is adaptive to the minor-diameter roll; the furnace temperature fluctuation range is greatly reduced; the heating and heat preservation stability is improved; and the heat treatment quality of the minor-diameter roll is improved.
Description
Technical field
The present invention relates to a kind of heat treating method of roll, be specifically related to the differential temperature heat treating method of the roll that a kind of diameter is less, belong to roll production field.
Background technology
In recent years, the Iron And Steel Industry fast development of China, rank the first in the world for years of iron and steel output.Meanwhile, the steel rolling technology of China is also in continuous progress, and steel rolling equipment is constantly updated, and the type of roll is more and more, and the performance requriements of breaker roll is also more and more higher.Under identical design mix and smelting condition, the performance of roll depends primarily on the quality of thermal treatment quality.In order to ensure that roll is in having high surfaces hardness and wear resistance, make core there is higher toughness, people have developed the differential temperature thermal treatment process of roll, and are being widely used aspect the thermal treatment of large-scale roller.
Different temperature heat treatment furnace generally can be divided into two kinds, vertical differential temperature stove and Horizontal different temperature stove, and wherein Horizontal different temperature stove is because the advantages such as easy to operate, homogeneous heating have obtained application more widely.Conventional Horizontal different temperature stove comprises two half bodies of heater that can fasten mutually, and the bottom of two and half bodies of heater arranges guide rail, and the motion by half body of heater on guide rail realizes the fastening of half body of heater and separating of half body of heater, closes stove and blow-on thereby realize.The two ends of body of heater arrange two fire doors, and two fire doors are for the roll neck of support roll, and fire door outside is also provided with holds roll neck and for making the support of roll rotation.In differential temperature stove, be distributed with multiple burners for heated roll, each burner is connected with gas line and air line by pressure controlled valve respectively.And each burner has an air-fuel ratio standard value, comprise air pressure standard value and gas pressure standard value.
When roll carries out differential temperature thermal treatment, generally first roll is placed on to preheating in preheating oven, insulation proceeds to after certain hour again carries out differential heating in differential temperature stove.When roll proceeds to differential temperature stove, the body of roll is placed in differential temperature furnace body inside, and the roll neck clamping at body of roll two ends is in the fire door of differential temperature stove, and the end of roll neck is installed on the support in fire door outside.When differential heating, rate of heating is than very fast, and will make roll slow circumvolve when heating, to ensure the homogeneity of heating.Differential heating is after certain temperature, carry out the insulation of short period of time, make the abundant austenitizing in roll top layer, and core is because the restriction that is subject to heat transfer rate does not also undergo phase transition, at this moment roll is taken out, quench, after temper, can make the top layer of roll have compared with high hardness and wear resistance and core still keeps higher toughness, thereby realize the differential temperature thermal treatment of roll.
In conventional art, when differential temperature thermal treatment, heat at the little fire of general use of the starting stage of differential heating.So-called little fire refers to that the coal gas flux of burner does not reach maximum value, thereby flame is less, the slow still good uniformity of heating; In the time that temperature is higher, generally the coal gas flux at burner place need to be adjusted to maximum value, use big fire to heat, promote on the one hand thermal convection in stove to make roller surface temperature even, improve on the other hand rate of heating, ensure the heat treated quality of differential temperature.
But the Heat Working Rolls of some minor diameters, due to the singularity of size aspect, cannot use conventional differential temperature stove to heat-treat, and design or buy special differential temperature Lu Youhuigei enterprise and bring extra economical load.So it is a good problem to study that searching one can be used existing installation to carry out differential temperature heat-treating methods to small diameter roller.
Utilizing traditional differential temperature stove to carry out the heat treated difficulty of differential temperature to small diameter roller is: a) heating efficiency of conventional differential temperature stove is the Roller Design that is 600mm～1000mm by roll diameter, and formulate flame debug standard according to the concrete structure of differential temperature stove and performance, and determine the standard value of flame air-fuel ratio, but in the time that processing roll diameter is less than the roll of 600mm, because the roll diameter of roll is thin, heat storage capacity is little, while heating according to the standard figures of flame air-fuel ratio, can cause the fluctuation range of furnace temperature to become large, cannot reach heating and insulation requirement; B) the roller neck diameter that conventional differential temperature stove design is produced is 350mm～750mm, if the roll neck of roll is less than 350mm, roll neck part cannot be installed on the support that makes roller rotational, also can cause the gap between roll neck part and differential temperature stove fire door too large simultaneously, the heat radiation of fire door place is too fast, easily cause roll on the low side near the portion temperature of fire door, cause thermal treatment quality defective.
Summary of the invention
The technical issues that need to address of the present invention are to provide a kind of differential temperature heat treating method of minor diameter high-chromium iron-cast roller, cannot shove charge when small diameter roller being heat-treated to solve traditional differential temperature stove, technical problem that furnace temperature fluctuation is large.
For solving the problems of the technologies described above, the technical solution used in the present invention is as follows.
The differential temperature heat treating method of minor diameter high-chromium iron-cast roller, comprises the following steps:
A) welding roll neck cover: a roll neck cover of suit welding on the excircle of the roll neck of roll, the external diameter of described roll neck cover coordinates with the clamping diameter of differential temperature stove fire door, and the length that roll neck overlaps is corresponding with the length of roll neck;
B) thermal pretreatment: will be welded with roll preheating in preheating oven of roll neck cover, 790 DEG C～810 DEG C of preheating temperatures, are incubated 22～24 hours;
C) differential heating: the air-fuel ratio of first adjusting each burner of differential temperature stove before differential heating, regulate the pressure controlled valve at each burner place, air pressure value is adjusted to 2/3rds of this burner air pressure standard value, gas pressure value is adjusted to 1/2nd of this burner gas pressure standard value; Then roll after treatment step b) is packed in differential temperature stove, in gap between roll neck cover and differential temperature stove fire door, fill up refractory fibre, open burner roll is heated to above 30 DEG C～100 DEG C of Ac3 temperature, rate of heating is 400 DEG C～700 DEG C per hour, is incubated 3～4 hours;
D) precooling treatment: stop heating, make roll be cooled to more than Ar3 temperature 20 DEG C～40 DEG C in differential temperature stove;
E) quench cooled: roll after treatment step d) is taken out, quench;
F) temper: roll after treatment step e) is packed into and carries out temper in tempering stove;
G) take off roll neck cover: roll after treatment step f) is taken out, the position of roll neck cover welding is interrupted after cooling, take off roll neck cover.
Further improvement of the present invention is: in described step a), and roll neck cover and roll neck running fit, tolerance clearance is 1mm～10mm.
Further improvement of the present invention is: in described step a), and roll neck cover and roll neck running fit, tolerance clearance is 3mm～8mm.
Further improvement of the present invention is: in described step a), between roll neck cover and roll neck, be connected in the mode of spot welding, in described step g), by grinder buffing, the position of welding interrupted.
Further improvement of the present invention is: in described step c), air pressure value is adjusted to 6Mpa～8Mpa, gas pressure value is adjusted to 0.9Mpa～1.2Mpa.
Further improvement of the present invention is: in described step b), warm comprises following several stage:
B1) roll is placed in to the preheating oven of 40 DEG C～60 DEG C and is incubated 5～8 hours;
B2) with the rate of heating that is not more than 10 DEG C per hour, roll is heated to 300 DEG C～400 DEG C, is incubated 10～15 hours;
B3) with the rate of heating that is not more than 20 DEG C per hour, roll is heated to 790 DEG C～810 DEG C, is incubated 22～24 hours.
Further improvement of the present invention is: described step b3) in, soaking time is 24 hours.
Further improvement of the present invention is: in described step e), the mode of quench cooled is air cooling, and the final temperature of quench cooled is 300 DEG C～400 DEG C.
Further improvement of the present invention is: in described step e), the final temperature of quench cooled is 350 DEG C～400 DEG C.
Further improvement of the present invention is: in described step f), temper comprises following operation steps:
F1) with the rate of heating that is not more than 30 DEG C per hour, roll is heated to 500 DEG C～560 DEG C, is incubated 10 hours;
F2) open tempering stove, make roll cool to room temperature in air;
F3) repeating step f1), f2) twice, finish.
Owing to having adopted technique scheme, the technical progress that the present invention obtains is as follows.
The present invention, by weld roll neck cover on the roll neck of small diameter roller, makes small diameter roller can meet the shove charge dimensional requirement of conventional differential temperature stove, has realized the normal shove charge of small diameter roller; The present invention, by adjusting the air-fuel ratio of conventional differential temperature stove, has improved the heating properties of differential temperature stove, makes intensification, insulation that small diameter roller can be stable in differential temperature stove, has dwindled the fluctuation range of furnace temperature, has ensured the smooth execution of small diameter roller thermal treatment process; The present invention, by making roll neck cover and adjusting differential temperature stove air-fuel ratio, has realized the object that uses conventional differential temperature stove to produce small diameter roller, has improved plant factor, has saved production cost.
In the present invention, by multiple intensifications, holding stage are set in thermal pretreatment step, and limit the heat-up rate in each stage, can ensure heat-processed evenly, slowly carry out, thereby avoid the crackle causing because rate of heating is too fast.Because roller diameter is thinner, and when differential temperature thermal treatment roll top layer and the core temperature difference larger, conventional quenching method easily causes roll top layer to occur crackle, in the present invention, the final temperature of quench cooled step is 300 DEG C～400 DEG C, be not cooled to below martensitic transformation starting point, and in the time of tempering for the first time, just start to occur martensitic transformation, can avoid roll in the time quenching, to cause cracking because structural stress is excessive.The temper stage, by three tempering, can be improved roll top layer martensitic transformation amount in the present invention, further improves the wear resistance on roll top layer, thereby improves roller performance.
Brief description of the drawings
Fig. 1: perspective view of the present invention;
Fig. 2: the structural representation of roll in Fig. 1.
Wherein: 1. roll, 11. bodies of roll, 12. roll necks, 2. differential temperature stove, 3. roll neck cover, 4. refractory fibre, 5. support.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is done further to describe in detail:
Embodiment 1:
A kind of differential temperature heat treating method of minor diameter high-chromium iron-cast roller, in the present embodiment, differential temperature stove 2 used is MC3 Horizontal different temperature stove, and the heating efficiency of this differential temperature stove is to be 600mm～1000mm, roll neck diameter in the Roller Design of 350mm～750mm according to roll diameter.In differential temperature stove, be furnished with more than 30 burner, the burner of different positions has different air-fuel ratio standard values, has different air pressure standard values and gas pressure standard value.Generally, the standard value of the air pressure of these burners is between 9Mpa～12Mpa, and the standard value of gas pressure is between 1.8Mpa～2.4Mpa.In the present embodiment, pending roll 1 is the high-chromium iron-cast roller of KmTBCr20Mo material, and as shown in Figure 2, the body of roll 11 diameters are 550mm to its structure, and length is 2000mm, and roll neck 12 diameters at body of roll two ends are 300mm, and length is respectively 1000mm.Because the diameter of roll neck part is less than 350mm, therefore cannot be installed to the support for making roller rotational, between roll neck and fire door, gap is excessive easily causes adding thermally labile, and furnace temperature fluctuation is large.In addition, because the roll diameter of pending roll is less than 600mm, can not adapt to the standard heating efficiency of MC3 Horizontal different temperature stove, therefore can not use conventional method to carry out differential temperature thermal treatment.
Differential temperature heat treating method of the present invention comprises the steps:
A) welding roll neck cover: suit welding one roll neck cover 3 on the excircle of roll neck 12, the internal diameter size of roll neck cover is 310mm, and outside dimension is 350mm, and the length of roll neck cover 3 is 1000mm, between roll neck cover and roll neck, is connected in the mode of spot welding.
B) thermal pretreatment: will be welded with small diameter roller preheating in preheating oven of roll neck cover, thermal pretreatment comprises following processing step:
B1) roll is placed in the preheating oven of 40 DEG C～60 DEG C and is incubated 5～8 hours;
B2) with the rate of heating that is not more than 10 DEG C per hour, roll is heated to 300 DEG C～400 DEG C, is incubated 10～15 hours;
B3) with the rate of heating that is not more than 20 DEG C per hour, roll is heated to 790 DEG C～810 DEG C, is incubated 24 hours.
C) differential heating: the air-fuel ratio of first adjusting each burner in differential temperature stove before differential heating, regulate the pressure controlled valve at each burner place, air pressure value is adjusted to 2/3rds of this burner air pressure standard value, gas pressure value is adjusted to 1/2nd of this burner gas pressure standard value, after adjustment, the air pressure value of these burners is between 6Mpa～8Mpa, and gas pressure value is between 0.9Mpa～1.2Mpa; Then roll after treatment step b) is forwarded in differential temperature stove, in the gap of roll neck cover and differential temperature stove fire door, fill up refractory fibre 4, the end of roll neck cover 3 is installed on support 5, opening burner heats again, workpiece is quickly heated up to 980 DEG C, rate of heating is 400 DEG C～700 DEG C per hour, is then incubated 3～4 hours, makes core of abundant austenitizing while of body of roll outer tissue still keep original structure state.
D) precooling treatment: stop heating, make roll be cooled to 850 DEG C in differential temperature stove.
E) quench cooled: roll after treatment step d) is taken out, and quench cooled in air, until roll is cooled to 350 DEG C.
F) temper: roll after treatment step e) is packed in tempering stove and carries out temper, and the technique of temper comprises the steps:
F1) with the rate of heating that is not more than 30 DEG C per hour, roll is heated to 500 DEG C, is incubated 10 hours;
F2) after insulation finishes, open tempering stove, make workpiece cool to room temperature in air;
F3) by step f1), f2) repeat twice, tempering finishes.
G) take off roll neck cover: roll after treatment step f) is hung out, and cooling solder joint is sliced off with sharpening machine afterwards, takes off roll neck cover.
Embodiment 2～5:
See the following form with the difference of embodiment 1, other conditions are all identical.
After tested, tolerance clearance between the fluctuation range of furnace temperature and roll neck and roll neck cover has certain dependency, in the time that tolerance clearance is between 3mm～8mm, while adopting the roll neck cover internal diameter size in embodiment 2,4,5, the fluctuation range of furnace temperature is between-3 DEG C～+ 4 DEG C, fluctuation range is little, and stove performance is more stable.In the time that tolerance clearance is below 3mm, the plus deviation of furnace temperature is larger, and in embodiment 3, the fluctuation range of furnace temperature is between-2 DEG C～+ 7 DEG C.When tolerance clearance is in the time that 8mm is above, the negative deviation of furnace temperature is larger, and in embodiment 1, the fluctuation range of furnace temperature is between-6 DEG C～+ 3 DEG C.Therefore, preferred tolerance clearance is between 3mm～8mm.
The roll hardness that embodiment 1,3,4 produces is HS85～88, the roll hardness that embodiment 2 and embodiment 5 produce is HS80～84, illustrate that working as thermal pretreatment soaking time is 24 hours, when quench cooled final temperature is 350 DEG C～400 DEG C, the roll carbide making is more even, can obtain better thermal effectiveness.
The present invention is by installing roll neck cover and adjusting burner air-fuel ratio for roll, can make heating efficiency and the small diameter roller of stove adapt, realize the differential temperature treatment production of small diameter roller, and significantly dwindle the fluctuation range of furnace temperature, promote the stability of heating and insulation, improved the thermal treatment quality of small diameter roller.
Claims (10)
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| CN201310327096.8A CN103436679B (en) | 2013-07-30 | 2013-07-30 | Differential temperature heat treatment method of minor-diameter high chromium cast-iron roll |
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| CN201310327096.8A CN103436679B (en) | 2013-07-30 | 2013-07-30 | Differential temperature heat treatment method of minor-diameter high chromium cast-iron roll |
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| CN103436679B true CN103436679B (en) | 2014-10-08 |
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104087742A (en) * | 2014-06-24 | 2014-10-08 | 河北钢铁股份有限公司唐山分公司 | Differential temperature heat treatment method for centrifugal compound high-chromium steel roller |
| CN104264055B (en) * | 2014-09-19 | 2016-08-24 | 山西太钢不锈钢股份有限公司 | A kind of Cold Work Roll Material and heat treatment method thereof |
| CN104313292A (en) * | 2014-09-24 | 2015-01-28 | 江苏共昌轧辊股份有限公司 | Differential temperature heat treatment method of D2 steel centrifugal composite roller |
| CN105063286B (en) * | 2015-07-25 | 2017-09-01 | 宜兴市永昌轧辊有限公司 | A kind of hardening and tempering process of minor diameter cold roll |
| CN105296735B (en) * | 2015-10-27 | 2018-01-05 | 中钢集团邢台机械轧辊有限公司 | A kind of roll differential temperature heat treatment method |
| CN105483353B (en) * | 2015-12-03 | 2018-03-23 | 中钢集团邢台机械轧辊有限公司 | The differential temperature heat treatment method of high carbon high speed steel roll |
| CN109439863B (en) * | 2018-12-29 | 2020-01-14 | 中国第一重型机械股份公司 | Heating process method for changing supporting roller soft belt |
| CN111676349A (en) * | 2020-05-12 | 2020-09-18 | 江阴兴澄合金材料有限公司 | Tempering process of round steel and application thereof |
| CN112725607B (en) * | 2020-12-22 | 2023-06-09 | 天津重型装备工程研究有限公司 | Anti-channeling device for differential temperature heat treatment, differential temperature furnace and differential temperature heat treatment method |
| CN114164339A (en) * | 2021-12-16 | 2022-03-11 | 河南中原特钢装备制造有限公司 | Production method for reducing heat treatment deformation of roller |
| CN115125385B (en) * | 2022-05-27 | 2024-02-20 | 洛阳中重铸锻有限责任公司 | Large-scale support roll differential temperature furnace mouth reconstruction and roll neck cotton-dressing protection method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102329944A (en) * | 2011-10-17 | 2012-01-25 | 中钢集团邢台机械轧辊有限公司 | Operating method of sequential differential temperature heat treatment for rollers of different diameters |
| CN102352431A (en) * | 2011-10-17 | 2012-02-15 | 中钢集团邢台机械轧辊有限公司 | Large-scale high-chrome cast iron roller permissible differential temperature heat treatment |
| CN202989238U (en) * | 2012-11-12 | 2013-06-12 | 鞍钢重型机械有限责任公司 | Shaft end lengthening device of minisize supporting roll |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS564606B2 (en) * | 1973-05-25 | 1981-01-31 |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102329944A (en) * | 2011-10-17 | 2012-01-25 | 中钢集团邢台机械轧辊有限公司 | Operating method of sequential differential temperature heat treatment for rollers of different diameters |
| CN102352431A (en) * | 2011-10-17 | 2012-02-15 | 中钢集团邢台机械轧辊有限公司 | Large-scale high-chrome cast iron roller permissible differential temperature heat treatment |
| CN202989238U (en) * | 2012-11-12 | 2013-06-12 | 鞍钢重型机械有限责任公司 | Shaft end lengthening device of minisize supporting roll |
Non-Patent Citations (1)
| Title |
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| JP特开昭50-7708A 1975.01.27 |
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